What message format does SOAP use?

SOAP, which stands for Simple Object Access Protocol, exclusively utilizes XML (eXtensible Markup Language) as its message format. This choice is fundamentally linked to SOAP's core design principles and its ability to enable structured information exchange between web services across different networks.

XML is highly suitable for SOAP due to its extensible nature, which allows developers to define their own tags and the structure of the data being exchanged. This flexibility ensures that various applications, regardless of their underlying technology or platform, can effectively communicate with one another by adhering to this standard format. Furthermore, XML allows for a clear hierarchy, making it easier to encapsulate complex data structures and ensuring that various types of data can be represented and transmitted.

The other formats mentioned are not supported by SOAP. CSV is a simple format used primarily for flat text data and does not support the complexities typically involved in web service interactions. HTML is mainly for the structuring of web pages and lacks the data serialization capabilities required by SOAP. JSON, while popular in modern web APIs for its lightweight syntax and ease of use, is not part of the SOAP standard, which is firmly rooted in XML.